Draw the context and 0 level data flow diagrams for a system that has following functions:

Build-Right is a company offering house building and property improvement services to the public. The proprietor of the company employs a number of skilled workers such as bricklayers, carpenters and plumbers. The proprietor manages the building projects himself, and occasionally helps with the construction work. Build-Right wants to computerise the management of building work. This includes processing of cost estimates, job scheduling, and payments as described below.

When a customer contacts the company to ask for an estimate, the proprietor makes a note of the customers contact details and records an outline of the proposed work. He agrees a date with the customer to view the property in order to give an estimate of the cost for the work.

When visiting the property on the agreed date the proprietor adds more detail to the outline of the proposed work.

Within three days of visiting the property the proprietor produces a fully detailed cost estimate and sends it to the customer.

If the customer agrees the estimate, the proprietor schedules a date to start the job (this is based on the size of the job and other jobs that have already been scheduled).

A few days before the agreed start date of a job, the proprietor contacts the customer to confirm the start date, and then orders the required building materials from suppliers to be delivered on the date the job starts.

At the end of the job the proprietor calculates the actual cost of the job to produce an invoice which is sent to the customer.

The customer has 30 days to pay the invoice.